1. Field of the Invention
The present invention generally relates to a keycap and a manufacturing method thereof. Particularly, the present invention relates to a patterned keycap having a selective protection layer and a manufacturing method thereof.
2. Description of the Prior Art
Keyboard is one of the important input devices for electronic devices, such as computer or mobile phone, while keyswitches are the most important parts constructing the keyboard. The keycap is the upmost part of the keyswitch and is generally manufactured by the injection molding technique. Firstly, the keycaps are formed corresponding to the keyswitches of a keyboard product and then engraved or printed with symbols or characters on the surface of each keycap. Finally, the keycaps are arranged on the substrate of the keyboard.
For the process of forming the symbol or character on the surface of the keycap, the conventional technique sequentially prints or sprays one or multiple layers of ink on the top face of the keycap and then forms the symbol or character by laser etching the ink layer(s). Finally, a protection layer is sprayed or printed to cover the ink layer(s) and a hardening treatment is performed on the protection layer. Such a forming process is time-consuming. Especially when multiple layers of ink are employed, the process variation is increased, decreasing the product yield of the keycaps.
In addition, if the protection layer is formed by spray coating, the protection layer will cover all exposed portions of the keycap, resulting in waste and non-uniform thickness of the protection layer caused by the spraying angle. If the protection layer is formed by the printing technique, the protection layer will cover only the top face of the keycap and cannot extend to the side face of the keycap (i.e. skirt of the keycap), making the user feel uneven touch during operation and affecting the input smoothness. Consequently, the spray coating or the printing technique cannot form a selective protection layer.
Taiwan patent publication no. 201338958 discloses a keycap having a layered ink structure formed by the in-mold release (IMR) technique. The IMR technique can greatly reduce the time for covering the layered ink structure onto the keycap and effectively improve the connection between the layered ink structure and the keycap to prevent the layered ink structure from peeling off. However, the protection layer cannot be formed by the IMR technique, and the keyboard usually includes multiple keycaps of different sizes which cannot be formed by injection molding in the same mold. That is, the keycaps of different sizes cannot be formed by the injection molding at the same time. Moreover, due to the restriction of the IMR technique, the gap between the cavities for accommodating the keycaps must be large enough, reducing the number of keycaps of the same size that can be processed by one mold, thus requiring more films and increasing the cost.
Moreover, for the IMR technique, the process involves the steps of releasing the upper mold and the bottom mold; thus the bottom face of the skirt cannot be covered (i.e. barb-like covering). The film (including the ink layer and the release layer) will generally create a parting line at the lower edge of the skirt; thus part of the ink layer will be likely removed during the removal of the release layer of the film. Consequently, the ink layer on the lower edge of the skirt will exhibit a zigzag or irregular shape, resulting in severe light leakage of the lighting keyboard.
Therefore, a method of manufacturing keycaps to solve the aforesaid problems and to achieve mass production of keycaps with user satisfaction is desired.